A proof-of-concept mini-survey, the eROSITA Final Equatorial-Depth Survey (eFEDS), was designed to demonstrate the survey science capabilities of eROSITA. The observations of the eFEDS field were performed between November 4th to 7th, 2019, during the Performance Verification (PV) phase. The eFEDS field is located at 126\(^{\circ }\)  < R.A. < 146\(^{\circ }\)  and \(-3^{\circ }\)  < Dec. < \(+6^{\circ }\) , covering a solid angle of approximately 140 square degrees137.9 deg\(^2\)  have a vignetting-corrected exposure time in the 0.5–2 keV band of 0.1 ks or more., with the similar depth as the full eROSITA All-Sky Survey in the equatorial regions. The average exposure times are \(\sim 2.2\)  ks and \(\sim 1.2\)  ks, before and after correcting for vignetting effects. The eFEDS field has also been observed with a broad array of multi-wavelength survey instruments, from optical to radio bands. In particular, the photometric data from the Hyper Suprime-Cam (HSC) Subaru Strategic Program
[1]}, [2]}, [3]}, [4]}, [5]}, [6]}, [7]}, [8]}, [9]}, [10]}, [11]}, DECaLS [12]}, SDSS [13]}, 2MRS [14]}, and GAMA [15]} surveys are used for cluster optical confirmation and redshift determination, and HSC, in particular, will provide weak lensing masses for eFEDS clusters (Klein et al., accepted, Chiu et al., submitted). Combining these with the X-ray properties measured with eROSITA data will enable the calibration of scaling relations between X-ray observables and cluster halo mass (Bahar et al., in prep, Ghirardini et al., submitted). Being the largest contiguous survey at the final Equatorial depth, it provides an ideal set-up for testing the predictions for the cluster number density in the survey and offers rich cluster science through its multi-wavelength coverage [16]}.
